Scientists have been trying to discover the secrets of these deceptively young-looking stars for decades. The youthful stars stay bright and blue while others around them are bloated and red, a sign that they’re nearing the end of their lives — but all of the stars in Messier 30 are thought to be about 13 billion years old.

"It's like seeing a few kids in the group picture of a rest-home for retired people," said Francesco Ferraro of the University of Bologna in Italy. "It is natural to wonder why they are there."

When two stars orbit each other, the smaller one siphons fresh hydrogen from the larger one, causing the smaller one to heat up and grow bluer.

But this strange form of vampirism isn’t the only way these stars defy signs of aging. Some stars retain their youth by colliding head-on with others. Scientists believe that about 2 billion years ago, the core of Messier 30 collapsed, causing stars to crash against each other, generating more of the hot young things.

"Our observations demonstrate that blue stragglers formed by collisions have slightly different properties from those formed by vampirism," said study team member Giacomo Beccari from the European Space Agency.